Control valve for double-acting piston type motors



March 14, 1950 s. E. GORDON CONTROL VALVE FOR DOUBLE-ACTING PISTON TYPE MOTORS Filed Jan. 18, 1945 3nventor JZa/Z Gordy.

(lttorneus Patented Mar. 14, 1950 UNITED STATES PATENT OFFlCE CONTROL VALVE FOR DOUBLE-ACTING PISTON TYPE MOTORS Saul E. Gordon, Detroit, Mich. Application January 18, 1945, Serial No. 573,407

12 Claims. (Cl. 121-465) The present invention relates to improvements in hydraulic transmission systems, and more particularly to a control valve therefor.

The primary object of the invention is to provide a control valve for a hydraulic fluid transmission system having a pressure fluid motor a control valve for fluid transmission having a double-acting piston motor and source of fluid under pressure with the control valve hydraulically connecting said motor and pressure supply so that the piston of the double-acting motor will be locked in position at the highest pressure developed in the system when-the control valve is operated to close the supply or admittance of fluid under pressure to either side of the double-acting piston in said motor.

Another object of the invention is to provide 2 Figure 1 is a longitudinal cross-sectional view of the valve embodying the inventionillustrating the relative parts thereof in a neutral position and showing the valve hydraulically connected to a double-acting piston type motor for controlling movement ofthe same;

Figure 2 is a longitudinal cross-sectional view of the valve shown in Figure 1 illustrating the initial movement of the valve spool to admit fluid under pressure to one side of the piston type motor; v v

Figure 3 is a similar view showing the manner in which the valve parts are related upon continued movement of the valve spool with the auxiliary movable valve spool thereof shifted a slight amount relative to the main valve spool; Figure 4 is a longitudinal cross-sectional view similar to Figures 1, 2 and 3 showing the arrange- .ment of the various valve parts upon further a control valve for a fluid transmission system having a double-acting piston type motor which will eliminate chattering of the piston when the fluid supply is cut off so that a more positive movement of the piston may be obtainedwhen the control valve is operated Another'object of the invention is to provide a control valve for fluid transmission system having a double-acting piston type motor so that the control valve may be operated to admit fluid under pressure to both sides of said fluid motor piston without creating fluid hammer in the system resulting from the sudden cut-off or cessation of fluid under pressure to said motor.

Another object of the invention is to provide a control valve for fluid systems having a pressure-operated double-acting piston type motor which will produce a cushioning effect when the valve is operated to cut off the supply of pressure fluid to either side of the double acting motor. 1

Another object of the invention is to provide continued movement of the valve spool and the position said spool assumes when the valve is fully opened;

Figure 5 is a longitudinal cross-sectional view of a valve similar to Figures 1 to 4 inclusive showing the initial movement of the valve parts during the return motion of the valve spool so as to out 01f the fluid return from the doubleacting motor prior to the cutofl of the supply thereto; and

Figure 6 is a longitudinal cross-sectional view showing the valve parts returned to their initial position.

In the drawing, attention is first directed to Figure 1 wherein there is shown a control valve constructed in accordance with the present invention' and generally designated by the reference character 5. The control valve is adapted to control the admission of fluid under pressure to a double-acting flu d motor 6 and said source of pressure may be in the form of a pump having a suitable drive and arranged with its inlets connected to the valve 5 and its outlets connected to the central portion thereof. The pressure fluid a control valve for 'fluid systems having a pressure fluid motor of the double-acting piston type which will produce a snap action during the initial opening of said valve so that greater control of the motor may be'provided and the sensitivity thereof increased.

Other objects and advantages of the invention will become apparent during the course oi. the following description of the accompanying drawing, wherein: Y

supply means forms no part of the present application and can be of conventional structure including a pumpand a return tank.

The valve 5 comprises a cylindricalcasing I having closure plugs 8 and 9 threaded in the end thereof to provide a. closed valve chamber and said casing l is provided with a longitudinal bore in extending axially therethrough to provide bearing surfaces for a spool valve or main valve member including opposed head portions II and I2 which are adapted to be slidably received in said bore and guided therein. The head portions H and i201! the spool valve are connected by means of a rod portion l3 which is formed intejgral with the guide head H and reduced and screw-threaded at its opposite end as at l4 for being threadedly received in a correspondingly threaded opening i6 in the guide head i2. A bore l in the guide head is adapted to receive a portion of the rod I3 and said bore is of the same diameter as said rod so that a shoulder will be formed thereon adjacent the screw threaded por- }tion l4 and form a stop for said rod. The end of the rod I3 is provided with a screw-threaded bore f to conform to the peripheral shape of the annular enlarged portion 43 of the sleeve 42. The

for receiving the threaded end ll of a control shaft l8 which projects through an opening IS in a guide boss 26 formed on the closure plug 9 and slidably guided therein. The slide rod i8 is adapted to be connected to the usual tracer arm of a conventional duplicating machine (not shown) so that as a model is moved beneath the tracer arm the rod |8 will be deflected and cause fluid under pressure to be admitted to the control cylinder 6 to thereby shift the table of the machine tool or the cutter thereof with respect to the work piece.

f The valve cylinder 1 is provided adjacent its ends with annular recesses or grooves 2| and 22- which are provided with radially extending threaded apertures 23 and 24 for receiving the threaded ends of fluid return pipes -25 and 26 which may be connected to a reservoir chamber and pressure pump in the usual-manner.

Formed between the annular recesses 2| and 22 30 and 3| which are provided with radially extending threaded openings 32 and 33 for receiving the threaded ends of pipe lines 35 and 36 which are connected to the'opposite ends of the motor cylinder 6 respectively. The motor 6 may be of any desired construction and as shown includes a cylinder 3'! closed at one end by a wall 38 and at the opposite end by a threaded plug 39. A piston 40 is reciprocably mounted in the cylinder 6 and is provided with a plunger rod 4| which extends through a bearing opening 42 in the plug 39. It will thus be seen that fluid under pressure admitted through the pipes 35 and 36 to the opposite piston 46 will cause the rod 4| to be reciprocated and it is intended to connect the rod 4| to a bed or table of a conventional machine tool (not shown) so as to move said table or bed beneath the cutter of'the machine tool in accordance with the movement of the .valve rod i8 controlled by the movement of a tracer thereon over the surface of a model.

Slidably mounted on the connecting rod portion l3 of the spool valve is an auxiliary valve member including a sleeve 42 having an annular nl r d portion 43 which is adapted to normally close the annular recess 21 when the valve is in its neutral position. The sleeve 42 is slightly shorter than the distance between the inner walls of the valve spool guides I and I2 so as to permit a slight sliding action therealong from the neutral position shown in Figure 1 toward annular groove 44 and detent 45 are arranged to permit slight sliding motion of the sleeve 42 without displacing the detent 45 entirely from said groove.

It will thus be seen that the valvespool guides H and I2 are adapted to cover the annular recesses 2| and 22 respectively and that the annular enlarged portion 43 on the sleeve 42 is adapted to cover the annular recess 21 so that upon move,- ment of the control rod It to the right or left, the annular enlarged portion 43 will uncover the annular recess 21 and permit fluid under pressure to pass to the opposite ends of the cylinder 6 through the pipe lines 35 and 36. Simultaneously either one of the enlarged valve spool guide portions II and |2fwill be moved a correspond- 3 ing amount to uncover one or the other of the annular recesses 2| and 22 and thereby connect the opposite ends of the motor cylinder 6 with one of the return conduits 25 or 26.

In operation, attention is directed to Figure 2 wherein the valve is shown with the parts thereof moved a slight amount during the initial movement of the control rod It. The arrow indicates the rod l6 and valve spool as being moved to the left so as to uncover the annular recess 21 and permit the breaking of the enlarged portion 43 of the sleeve 42 so as to admit pressure fluid to the pipeline 36 to the right hand end of the motor cylinder 6 and cause said piston 40 to be moved to the left. It is noted that the valve guide portion H has been moved a slight amount to connect the opposite end of the motor cylinder 6 with the return pipe 25 through the break between said enlarged valve spool guide portion H and annular recess 2|. When the valve spool has thus been moved. the fluid pressure will be greater on the right hand side of the enlarged portion 43 of the sleeve 42 and will cause the sleeve to shift to the position shown in Figure 3 relative to the valve spool and the guides ii and i2 thereof against the resilient action of the spring-loaded detent 45. Upon continued movement of the control'plunger l8 as shown in Figure 4, the sleeve 42 will follow the movement of the connecting rod portion |3 of the valve spool and thereby completely open and break the annular recess 21 as well as the annular recess 2|. During the either end of the connecting rod portion |3 of- I the spool valve. The connecting rod portion I3 is provided with. an annular groove 44 intermediate its ends for receiving a detent 45 such as a ball or the'like which is retained within a entre movement of the valve spool to the left as indicated in Figures 2 to 4, inclusive, the movable sleeve 42 is urged to the left by the diflerence in the pressure on the right and left hand sides of the enlarged portion 43 thereof.

When the movement of the control rod I8 is arrested either by mechanical 'or manual means, the valve spool and its movable sleeve 42 will remain in the position shown in Figure 4. When the motion of the control rod I8 is reversed as shown in Figure 5, so as to move the valve spool to the right as ind'cated bythe arrow,- the annular recess 2| will be closed before the enilarged portion 43 of the movable sleeve 42 has moved a suflicient distance to completely close the annular recess 21 and thereby immediately close of! the return port from the motor I through the valve by way of the annular recess 2| and return pipe 23 so as to retain the piston 40 in its predetermined position without creating hammer in the system and at the same time preventing backlash. As the pressure-from the return pipe 35 through the threaded openin 32 becomes equal to the pressure on the right hand side of the enlarged portion 43 of the sleeve 42, said sleeve is shifted to theoright by reason of the yielding spring action of the spring-loaded detent 45 so as to cause said enlarged portion to flnally cut 01! the annular recess 21 when said movable sleeve 42 comes to rest in the position shown in Figure 6 wherein the detent is received fully within the annular groove 44. As shown in Figure 5, the annular sleeve 42 and enlarged portion 43 thereof is on the verge of being shifted to the right so as to close off the passageway between the inlet 29 and threaded outlet 33 but it is to be noted that the enlarged guide portion ll of the valve spool has already shifted to close ofl the passageway between the return threaded port 32 and return threaded reservoir receptacle.

It will thus be seen that a snap action is provided for cutting oi! the pressure fluid supply to the motor 6 after the return passageways have been cut off by either one of the enlarged guide portions II and I2 of the valve spool so as to arrest the movement of the piston 40 so as to eliminate chatter and hammer before the pressure fluid supply is cut oil.

Obviously, the same operation applies when the control or plunger rod I8 is moved from the neutral position shown in Figure 1 in a direction opposite the direction of movement shown in Figure 2. That is to say, when the rod 18 is moved to the right sufficiently to uncover the annular recess 21, and the annular recess 22, the pressure will build up on the lefthand side of the annular enlarged port on 43 of the movable sleeve 42 to such an extent as to shift the sleeve to the right and permit fluid under pressure to be admitted to the left-hand end of the motor cylinder 6 through the pipe 35 and returned through the pipe 36, annular recess 22 and pipe 26 to the supply reservoir or other receptacle.

It is pointed out that in valves of the type shown for controlling the movement of a double acting piston of a fluid pressure motor, chattering and hammer occur when the supply is cut of! suddenly, which sudden cutoff creates a series of pressure waves varying from plus to minus which build up excessive pressure and create chattering in the system. By cutting off the return passage first, and then cutting off the pres- .sure fluid supply, as described and pointed out in the above application, the chattering and hammer are eliminated and the piston 40 may be brought to a predetermined position within the cylinder 31 and arrested at the desired location without vibratory motion being imparted thereto from the series of pressure waves when the movable sleeve 42 is finally brought into position so that the enlarged portion thereof 43 closes oil the annular recess 21 and the break between the threaded inlet port 38 and either one of the threaded ports 32 and 33 depending upon the motion of the valve spool.

Thus by reason of the fact that the return line of the pressure fluid is cut off, prior to the cut off of the fluid admitted to the cylinders 31, the plunger rod 4| may be moved with a nicer degree of accuracy for guiding a tool or the Use over a piece of work in response to movement of the'control rod l8 which'may be connected to -a tracer movableover a model or other conventional duplicating device.

It is to be understood that the control rod l8 may be operated manually so as to shift the valve spool and that the piston plunger 4| will be connected to the work bed of a conventional machine tool for controlling the movement of the work bed under a stationary cutter as in the case of a work feedfor various machine tools such as milling tools and the like.

It is to be understood that the form of the invention herewith shown and described is to be taken as a preferred embodiment of the same and that various changes may be made in the shape, size and arrangement of parts without departing from the spirit of the invention or the scope of the subjoined claims.

What I claim is:

1. In a hydraulic transmission system including a reversible motor adapted to be operated by pressure fluid, a valve casing hydraulically connected to said motor, a main valve member therein controlling the outgoing fluid flow to one side of said motor and the return fluid flow from the other side thereof, and an auxiliary valve member in said casing controlling the pressure fluid inlet flow and having opposing areas thereon exposed to the pressure of said outgoing fluid and return fluid respectively, said auxiliary valve member being responsive to the differential pressure on said opposing areas to shift to a position increasing the outgoing fluid flow to said motor over the return fluid flow from said motor.

- 2. In a hydraulic transmission system including a reversible motor adapted to be operated by pressure fluid, a valve casing hydraulically connected to said motor, a main valve member therein controlling the outgoing fluid flow to one side of said motor and the return fluid flow from the other side thereof, and an auxiliary valve member in said casing controlling the pressure fluid inlet flow and having opposing areas thereon exposed to the pressure of said outgoing fluid and return fluid respectively, said auxiliary valve member being responsive to the differential pressure on said opposing areas to shift to a position increasing the outgoing fluid flow to said motor over the returnfluid flow from said motor, said auxiliary valve member being further responsive to the equalization of pressures on said opposing areas and to the termination of return fluid flow from said motor to terminate said outgoing fluid flow to said motor.

3. In a hydraulic transmission system including a reversible motor adapted to be operated by pressure fluid, a valve casing hydraulically connected to said motor, a'main valve member therein controlling the outgoing fluid flow to one side of said motor and the return fluid flow from the other side'thereof, and an auxiliary valve member in said casing movable by said main valve member and also movable relatively thereto, said auxiliary valve member controlling the pressure fluid inlet flow and having opposing areas thereon exposed to the pressure of said outgoing fluid and return fluid respectively, said auxiliary valve member being responsive to the motion of said main valve member and also to the differential pressure on said opposing areas to shift to a position increasing the outgoing fluid flow to said motor over the return fluid flow from said motor.

4. A control valve for double-acting hydraulic motors comprising a valve cylinder having a plurality of axially-spaced fluid control ports including a pair of outer exhaust ports, a pair of intermediate motor-control ports between said outer ports and a pressure fiuid supply port be tween said intermediate ports, a reciprocable valve stem with a pair of fixed outer valve heads and a relatively movable valve head therebetween, said heads being operable to cover and uncover said ports upon reciprocation of said stem, and means for limiting the range of motion of said movable head along said stem.

5. A control valve for double-acting hydraulic motors comprising a valve cylinder having a plurality of axially-spaced fiuid' control ports including a pair of outer exhaustports, a pair of intermediate motor-control ports between said outer ports and a pressure fluid supply port between said intermediate ports, a reciprocable valve stem with a pair of fixed outer valve heads and a relatively movable valve head therebetween, said heads being operable to cover and uncover said ports upon reciprocation of said stem, means for limiting the range of motion of said movable head along said stem, and resilient means, normally urging said relatively movable head towards a predetermined position on said stem and responsive to the attainment of a predetermined pressure upon one side of said movable head for releasing said movable head for motion along said stem.

6. A control valve for double-acting hydraulic motors comprisinga valve cylinder having a plurality of axially-spaced fluid control ports including a pair of outer exhaust ports, a pair of intermediate motor-control ports between said outer ports and a pressure fluid supply port between said intermediate ports, a reciprocable valve stem with a pair of fixed outer valve heads and a relatively movable valve head therebetween,

said heads being operable to cover and uncover said ports upon reciprocation of said stem, means for limiting the range of motion of said movable head along said stem, and resilient means normally holding said relatively movable head in a temporarily fixed position on said stem and responsive to the attainment of a predetermined pressure upon one side of said movable head for releasing said movable head for motion along said stem.

7. A control valve for double-acting hydraulic 5 motors comprising a valve cylinder having a plurality of axially-spaced fluid control ports includ- I ing a pair of outer exhaust ports, a pair of intermediate motor-control ports between said outer ports and a pressure fluid supply port between said intermediate ports, a reciprocable valve stem with a pair 01' fixed outer valve heads and a relatively movable valve head therebetween, said heads being operable to cover and uncover said ports upon reciprocation of said stem, means for go limiting the range of motion of said movable head along said stem, and yielding detent means interconnecting said relatively movable head and said stem and responsive to the attainment of a predetermined pressure uponone side of said movable head for releasing said movable head for motion along said stem.

8. A control valve 'for double-acting hydraulic motors comprising a valve cylinder having a plurality of axially-spaced fluid control ports including a pair of outer exhaust ports, a pair of intermediate motor-control ports between said outer ports and a pressure fluid supply port between said intermediate ports, a reciprocable valve stem with a pair of fixed outer valve heads and a relatively movable valve head therebetween, said heads being operable to cover and uncover said ports upon reciprocation 01' said stem, means for limiting the range of motion of said movable head along said stem, a detent portion and a detent-receiving porti n releasably holding said movable head in a temporarily fixed position on said stem, one of said portions being on said movable head and the other portion being on said stem, and yielding means for urging said detent portion into said detent-receiving portion.

9. A control valve for double-acting hydraulic motors comprising a valve cylinder having a plurality of axially-spaced fluid control ports including a pair of outer exhaust ports, a pair of intermediate motor-control ports between said outer ports and a pressure fluid supply port between said intermediate ports, a reciprocable valve stem with a pair of fixed outer valve heads and a rela tively movable valve head therebetween, said heads being operable to cover and uncover said ports upon reciprocation of said stem, means for limitingthe range of motion of said movable head along said stem, a detent portion and a detentreceiving portion of V-shaped cross-section releasably holding said movable head in a temporarily fixed position on said stem, one of said portions being on said movable head and the other portion being on said stem, and yielding means for urging said detent portion into said detentreceiving portion.

10. A control valve for double-acting hydraulic motors comprising a valve cylinder having a plurality of axially-spaced fluid control ports including a pair of outer exhaust ports, a pair of intermediate motor-control ports between said outer ports and a pressure fluid supply port between said intermediate ports, a reciprocable valve stem with a pair of fixed outer valve heads and a relatively movable valve head therebetween, said heads being operable to cover and uncover said ports upon reciprocation of said stem, means for limiting the range of motion of said movable head along said stem, an annular detent portion and a detent-receiving portion of V-shaped cross-section releasably holding said movable head in a temporarily fixed position on said stem, one of said portions being on said movable head and the other portion being on said stem, and yielding means for urging said detent portion into said detent-receiving portion.

11. A control valve for double-acting hydraulic motors comprising a valve cylinder having a plurality of axially-spaced fluid control ports including a pair of outer exhaust ports, a pair of inter-' mediate motor-control-ports between said outer ports and a pressure fluid suppl port between said intermediate ports; a reciprocable valve stem with a pair of fixed outer valve heads and a relatively movable valve head therebetween, said heads being operable to cover and uncover said ports upon reciprocation of said stem, means for limiting the range of motion of'said movable head along said stem, said range -limiting means comprising head-connected axially extending sleeve and' having stop poring the outgoing fluid flow to said motor over the 0 Number Name Date return fluid flow from said motor, said auxiliary 745,520 Prescott Dec. 1,1903 valve member being further responsive to the 849,958 Abrego Apr. 9, 1907 equalization of pressures on said opposing areas 1,775,856 Hauser Sept. 6, 1930 and to the motion of said main valve member ter- 1,935,119 Guild Nov. 14, 1933 in said casing movable by said main valve memto terminate said outgoing fluid flow to said mober and also movable relatively thereto, said auxtor.

iliary valve member controlling the pressure fluid SAUL E. GORDON. inlet flow and having opposing areas thereon exposed to the pressure of said outgoing fluid and REFERENCES CITED return fluid respectively, said auxiliary valve The following references are of record in the member being responsive to the motion of said file of this patent: main valve and also to the diflerential pressure on said opposing areas to shift to a position increas- UNITED STATES PATENTS minating said return fluid flow from said motor 2,154,718 Bannon Apr. 18, 1939 

